Apparatus and System to Counter Drones Using Semi-Guided Fragmentation Rounds

ABSTRACT

A battlefield weapon system is proposed to counter the threat posed by small drones. The system uses a standard .50 caliber machine gun firing explosive rounds, to create a flak bombardment to bring down the drone. A control system causes the round to fragment as it approaches the range of the target. The direction in which the round is fired is controlled manually by the gunner. The system is fully portable for dispersed deployment among infantry.

CROSS-REFERENCE TO RELATED APPLICATION

None.

FIELD OF THE INVENTION

This invention is related to battlefield weapons systems and the threat posed by small UAVs (Drones).

BACKGROUND OF THE INVENTION

The low cost and ready availability of simple remote-piloted aircraft systems (RPAS) presents the enemy with an efficient means to achieve battlefield tactical reconnaissance and strike capabilities that would have been unheard of ten years ago.

In an asymmetric threat scenario, simple, low-cost aircraft remote piloted aircraft (whether directly purchased from hobbyist suppliers, or manufactured along similar lines) can be modified with relative ease to include video downlink and to deliver:

-   -   explosive ordnance     -   precision, close range shot (rifle, pistol, shotgun)     -   all manner of chemical, nuclear or biological agents     -   close-up reconnaissance photography, possibly with GPS mortar,         artillery and sniper spotting

Under a symmetric threat scenario, all of the above-mentioned capabilities are presented, together with:

-   -   threat from semi-autonomous drone aircraft     -   threat from super-miniature insect- and bird-like aircraft     -   target marking for terminal guidance of smart munitions.

The small RPAS carries with it the possibility to inflict significant damage, while being difficult to counter. The effective target size may well be as little as 0.01 m2, that is to say 50 times harder to hit than a person, as well as moving fast and changing direction. Even in for a well-armed and fully supported engagement team, none of the weapons available to the infantryman or rifleman (rifle rounds, hand grenades, RPGs, machine guns, mortar, anti-aircraft missiles, artillery or airstrikes) are effective against this threat.

The laser-powered weaponry that is currently in trials and early deployment is expensive and not readily mobile. Truck-mounted systems are not compatible with modern mobile warfare. The need is to create an effective weapon system that can be accessible to every infantryman and practically deployable at the squad or platoon level. In short, the wish list is:

-   -   Effective     -   Portable (backpack)     -   Cost-effective and therefore readily deployable

Prior art includes various drone-against-drone systems. Patent U.S. Pat. No. 9,085,362 B1 describes a system for deploying a net from one drone, to entangle another. Also under trials are systems that track the target and provide automatic guidance of a steerable 50 mm projectile to attack a drone. These systems all share the disadvantage that they are not readily deployable among small mobile, combat units on the battlefield.

Prior art also extends to shotguns. These provide the spread needed to engage a small target but lack effective range.

It is an object of this invention to provide foot soldiers with a practical means to counter the threat posed by drones.

It is an object of this invention to provide a drone countermeasure system that is compatible with, and extends the capabilities of, existing equipment that is carried by foot soldiers.

It is an object of this invention to provide a drone countermeasure system that is inexpensive compared to the current alternatives.

It is an object of this invention to provide a drone countermeasure that is effective over a range of many hundreds of meters.

It is an object of this invention to provide foot soldiers with a drone countermeasure system that can be carried in back backs without undue additional weight.

It is an object of this invention to provide a drone countermeasure system that can function effectively against a multitude of other targets.

It is an object of this invention to provide a drone countermeasure system that incorporates safety and arming features that protect the soldiers on the battlefield that use the system and mitigates the hazards presented by unexploded ordnance.

SUMMARY OF THE INVENTION

Modified .50 caliber rounds fired from a standard M2 machine gun set up a “flak” field that will counter small RPAS. The weapon is aimed manually, and the round is provided with automated detonation timing so as to create a fragment field at the correct range on target. The gunner “walks” the explosion bursts onto the target in a similar manner to the use of tracer rounds, but with the bursts giving a clear indication of the point where the arc of fire intersects the plane defined by the range of the target.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the simplest implementation using a delay timer to determine the point of fragmentation of the round.

FIG. 2 shows the creation of a fragmentation cone caused by the round fragmenting before it reaches the target.

FIG. 3 shows the addition of a radio transponder to provide feedback control of detonation range.

FIG. 4 shows the use of laser measurement of the range of the fragmentation round at the point of fragmentation.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, the drone to be targeted 1 is sighted with a laser rangefinder 2 that obtains range to target information using the laser beam 3. The range information is fed to a control unit 4. The control unit transmits a programming code from a coil 5 that is mounted at the muzzle of a machine gun 6. A special bullet, the fragmentation round 7, is programmed as it passes through the coil. The coil carries an electrical current and is magnetically coupled to circuitry inside the round. The circuitry detects the magnetic field and the delay time is programmed according to the signal that is encoded using the magnetic field. The program information determines the delay time before the fragmentation of the round.

The machine gun is a fifty-caliber type, and the rounds are arranged so that every fourth round is a fragmentation type, the others being conventional.

The rounds are fused in part by the timer programming from the coil 5. Until the round has passed through the coil 5, it will be safe and unable to explode prematurely.

The critical event is to cause the round to disintegrate as it approaches the target at close range. Assuming a round with mass 1,800 grains splits into 100-200 fragments, the individual pieces will then have 9-18 grain mass (about one-sixth to one-third that of a 0.22 caliber round) and be traveling at perhaps 1,600 ft./s as they meet the target. Assuming a target size of 0.1×0.1 m, a fragment field spread of 1 m=1 m would give an expected rate of 1-2 hits per round on target.

A single splinter of this size and velocity will be lethal when impacting within the vulnerable target area of the drone. The drone specifically considered in this scenario is low-cost and will not be carrying armor plate. The likely penetration requirement will be 2 mm of ABS plastic and/or 1 mm aluminum, to fatally damage control electronics, fan blades, electric motors, batteries and airframe components.

The fragmentation of the round ideally should occur some meters in advance of impacting the target. Most of the fragment kinetic energy is derived from the velocity of the round as it approaches the target. The size of fragmentation charge is kept small—ideally low 100 feet per second.

FIG. 2 shows how the fragments spread out in a cone shape. The bullet approach path 1 is in the general direction of the drone 2. The fragmentation point 3 is some distance before the drone and the fragments spread out in a cone shape 4. The cone geometry, number of fragments, fragmentation charge size and rate of fire are optimized to achieve the best compromise between weapon system effective range, accuracy and effectiveness.

A major advantage of the system, compared with a shotgun, is that the effective range can be many hundreds of meters.

FIG. 3 shows an enhancement of the system to improve range accuracy using radio communication with the fragmentation round. As before, a laser rangefinder 2 targets the drone 1 using a laser beam 3 to determine the target range and possibly motion. Range information is fed to the controller 4 that programs the fragmentation rounds 7 fired from the machine gun 6 using the coil 5. A radio 9 sends transponder challenges 8 repeatedly to the round. The transponder on the round activates shortly before fragmentation and the measured transponder response time is reported to the controller 4. The time so measured enables the controller to correct the time delay programming of successive rounds to cause the rounds to fragment accurately at the desired range ahead of the drone.

Alternatively, also with reference to FIG. 3, the radio link 8 may be used directly to control the moment of fragmentation of the round according to measured range on the radio link 8.

A further variation in fragmentation control time is depicted in FIG. 4. Here the laser rangefinder 2 targets the drone 1 using a laser beam 3. Again, the controller 4 programs the fragmentation rounds 7 using coil 5 momentarily after they are fired from machinegun 6.

Instead of using radio communications, though, a laser link 8 provides two-way communication with the round to determine range at the moment of fragmentation or to directly command the fragmentation event. 

1. As battlefield weaponry, a counter unmanned aerial system (CUAS), said system comprising: a. A man-portable machine gun or other weapon having automatic fire-and-reload that is capable of firing a succession of projectiles toward a target; b. Fragmentation rounds. A fragmentation round is a bullet or projectile that is intended to be fired from said machine gun and incorporates some means of breaking itself apart or being broken apart into small pieces at a controlled moment in time for the purpose of disabling damaging and or destroying the target; c. A means to control the timing or range of the fragmentation of the fragmentation rounds, such means being wholly or partially automated; d. A range finder to determine the range of the target from said machine gun or other datum; e. A control unit that accepts target range information and possibly other inputs to compute the timing of said round fragmentation with respect to target range and which is provided with the means of controlling the range and or timing of the said round fragmentation.
 2. The system of claim 1 wherein the fragmentation rounds are interspersed with regular rounds or rounds of a different type, on the ammunition belt or magazine.
 3. The system of claim 1 wherein each fragmentation round is programmed during or after firing to arm it.
 4. The system of claim 1 wherein each round is programmed during or after firing to set a delay time after which the round will fragment.
 5. The system of claim 1 wherein each round is programmed during or after firing with information that will improve the resistance of the communication system to jamming or other interference.
 6. The system of claim 1 wherein a coil is magnetically coupled with the round for purposes of programming the round.
 7. The system of claim 1 wherein a coil is magnetically coupled with the round for the purposes of arming the round.
 8. The system of claim 1 wherein the controller applies range prediction based on target motion.
 9. The system of claim 1 wherein monitoring of atmospheric conditions is applied as an input in the control of fragmentation timing.
 10. The system of claim 1 wherein measurement of the range at fragmentation of a round is used as part of a feedback mechanism within the computation of the required time delay to fragmentation for a subsequent round or rounds.
 11. The system of claim 1 wherein the firing of the said fragmentation round is used in the arming of the fragmentation charge.
 12. The system of claim 1 wherein the rifling-induced spin of the fragmentation round is used in the arming of the fragmentation charge.
 13. The system of claim 1 wherein the cessation of the rifling-induced spin of the said fragmentation round is used to make safe the fragmentation charge.
 14. The system of claim 1 wherein the machine gun is provided with a deflection sight or sight adjustment, such that some combination of the range of the target, azimuthal or elevation rate of the gun and atmospheric condition measurement are used to assist the machine gunner in aiming of the machine gun.
 15. The system of claim 1 wherein machine vision is used to determine the direction of the target to assist the range finding system.
 16. The system of claim 1 where Doppler effects are used to discriminate the target by its gross motion or by its internal moving parts for the purposes of determining target range.
 17. The system of claim 1 wherein the range of the round immediately prior to fragmentation is known to the controller by means of secondary radar.
 18. The system of claim 1 wherein the range of the round immediately prior to fragmentation is known to the controller by means of primary radar.
 19. The system of claim 1 wherein there is communication with the round by laser.
 20. The system of claim 1 wherein the fragmentation of the round is commanded directly by remote communications link. 